On Tue, Jan 19, 2021 at 06:24:49PM +0100, Bodo Stroesser wrote: > > I had a second look into math.h, but I don't find any reason why round_up > could overflow. Can you give a hint please? #define round_up(x, y) ((((x)-1) | __round_mask(x, y))+1) ^^^^^ That +1 can overflow It looks like it would not be so bad to implement some check_round_up_overflow() if people prefer Jason